You can download installation files and ISOs of any of the latest versions of VMWare Tools for each released version of ESX:

→ https://packages.vmware.com/tools/esx/index.html

This is useful if you need support for a certain OS version but are not able to upgrade the ESX host in order to get it (e.g. Windows 10 support on ESX 5.5 "non-u3").

Note that, although officially unsupported, VMWare Tools is technically backwards compatible, meaning you can install a newer version on a guest running on an older ESX host.